The present invention relates to a tool for breaking a vacuum in a preserving jar closed with a screw cap, said tool comprising an oblong handle, which at one end has a portion for engaging the periphery of the cap, and a jaw for engaging the lower edge of the cap.
A tool of this kind is known from DE patent application No. 38 22 745. In this tool the portion for engaging the cap comprises two essentially perpendicular arms tapering towards the ends, and the edges which are intended to engage the cap form a small angle with each other in such a way that each arm only contacts the rounded outer rim of the cap at a single point.
When the tool is used, the jaw is advanced towards the cap, the free end of the jaw reaching under the edge of the cap while the portion with the two arms abuts the rim of the cap, the handle extending diametrically across the cap. The handle is then pressed down against the cap to pivot about a line through the two contact points between said arms and the cap, whereby the jaw is intended to engage the edge of the cap and deform it elastically and thus break the vacuum in the jar.
The tool suffers, however, from the major drawback that the handle, in particular when used for breaking a vacuum in a jar with a comparatively big diameter, will abut the upper rim of the cap at a point diametrically opposite the jaw, before the jaw has lifted the edge of the cap sufficiently, which results in the vacuum not being broken. On account of the shapes-of the two arms the tool tends to slide away from the cap during the pivoting movement, which further amplifies the above-mentioned drawback.
The tool also suffers from the disadvantage that it is difficult to simultaneously hold the tool and to present it to the cap as the fingers cannot grasp the handle, as the fingers would then be squeezed between the handle and the cap when the handle is pressed against the cap.
The object of the invention is to provide a tool of the type mentioned by way of introduction, which does not have the above-mentioned drawbacks and which is designed in such a way that the user intuitively understands how to use it.
This object is met according to the invention by a tool which has as characteristics in that the portion for engaging the cap is adapted to bear on the upper surface of the cap, that the mouth of the jaw is turned away from the other end of the handle, that the free end of the jaw forms a concave arc of a circle, and that between the handle and the jaw is a guide means in the shape of a slot forming a concave, cirular arc. In this embodiment the fingers may grasp. the handle of the tool, and the end of the tool with the jaw may in a natural way be advanced towards the rim of the cap, where it is guided to the rim by the concave, circular, cylindrical guide slot, the radius of which is of the same order as the radius of commonly used caps. The circular arc formed by the free edge of the jaw likewise has a radius corresponding to the radius of the neck of the commonly used jars. This makes it possible for the jaw to reach all the way to the jar over its whole width, and it is thereby ensured that the jaw safely rests on the lower side of the rim of the cap and not simply contacts the rim at a single point. The handle is then lifted, slightly thereby pivoting about the line of Contact between the upper side of the cap and the portion bearing on the cap. By this movement the jaw grips the lower edge of the cap and gives it an elastic deformation sufficient for breaking the vacuum in the jar. As the tool according to the invention bears on the upper side of the cap and not like the known tool the rounded outer rim of the cap, it does not, when used, like the known tool, tend to slide away from the cap.
In a preferred embodiment the portion for engaging the cap may be a plane surface in the shape of a circular segment. By this embodiment a line contact is established during the pivoting of the tool between the edge of the plane surface constituting the chord of the circle segment and the upper side of the rim of the cap, which is usually a plane, annular surface. Such a line contact is more gentle on the cap than the point contact occurring in case of the known tool when used.
In another embodiment the circular segment may have such a size that when the tool is used it spans over two thread sections in the screw cap. The thread on the commonly used jars is a quadruple thread in case of small jars and a sextuple thread in cane of big jars. As the pitch of the thread is comparatively big, and the portion of the neck of the jar provided with threads comaparatively short, each thread or thread portion only extends over a comparatively small part of the circumference of the neck. The cap does not have an actual thread, but the rim of the cap facing downwards is flanged with a view to reinforcing the rim, except for four or six sections positioned equally spaced along the circumference, where the edge forms a flap facing the centre of the cap. When screwing on the cap these flaps engage the threads of the jar and therefore act as a kind of interior threads.
Tests have shown that it Is advantageous that the circular segment span over two thread sections in the cap in order to obtain a suitable elastic deformation of the rim of the cap for breaking the vacuum in the jar if the circular segment spans over more thread sections, the pivoting line will, when the tool is used, be closer to the centre of the cap, and the lever between the pivoting line and the jaw will therefore become so long, that a user applies too large a force to break the vacuum and counteracts this by steadying the jar with the other hand, whereby the rim becomes permanently deformed. If, however, the circular segment spans over a smaller area, for instance only a single thread section, the force applied by the user to the rim of the cap will be concentrated on a small area, and there in a risk that a permanent deformation of the rim of the cap will occur.
In a further embodiment the length of the jaw may be adjustable. Even though most jars on the market are provided with caps of standard size, caps having an extra high rim may also be found on the market. In said embodiment the tool may also be used for such jars, in addition to being used for the more common jars.